Class 6: Fat and Oils

fat are found in the form of _____________

triglyceride

true or false: Storage conditions depend on type of fat

true

what differ fiat from oil?

Fats: solid at room temp; usually from animal sources Oils: liquid at room temp; usually from plant sources

what are some fat replacement?

- apple sauce - beans - shredded zucchini - bananas - tofus

what are some advantage of cooking with coconut oil?

- good for frying (high smoking point) - give food a nutty flavour

formation of ω-6, ω-3 eicosanoid

- linoleic acid: elongation: arachidonic-->ω-6 - linolenic acid (ALA): elongation: EPA --> ω-3 eicosanoid or another elongation --> DHA

shredded zucchini

- lock in moisture in muffins and bread

how degree of saturation is related to melting point?

- low degree (unsaturated): lower MP - saturated: high MP

what are some other sterol apart from cholesterol?

- phytosterol : in plant

what differ refined and unrefined oil?

- unrefined oils are not processed further after pressing - Refined oils are chemically and physically processed to remove undesirable components from the oil

how antioxidant prevent oxidative stress?

1. Being oxidized themselves 2. Donating their hydrogen to a FA 3. Sequestering metals (chelating agent)

what is the recommended intake of unsaturated fat each day you need to take? including oil used for cooking, salad dressing, margarine, mayonnaise.

2-3 tbsp (30 - 45 mL)

what is the most common fatty acid chain length?

4-24 most common: 16 or 18

where can you find cholesterol in diet?

ANIMAL ONLY: meat, poultry, fish and fish roe, organ meats, dairy products, egg yolk

what is fatty acid notation for linoleic acid?

C18:2n-6

what is rancidity

Chemical deterioration of fats that gives off-flavours and rancid odours

what are some tips and tricks for low fat cooking?

Choice of equipment: § Non-stick frying pans : eliminates need for oil (or at least not as much) § Parchment paper: eliminates need for greasing Choice of cooking methods: § Steaming § Grilling, Baking, or Poaching instead of Frying choose ingredient wisely, use low fat replacement preparation

what are oil that are high in saturated fat

coconut oil, butter , palm oil

how hydrolytic rancidity happen?

Exposure to water, catalyzed by heat and lipase enzyme--> hydrolyze TG into smaller subunit --> rancid flavour (deep-frying, butter left at room temperature)

How do we use fats?

In food preparation (oil for frying) food formulation (as an ingredient) added directly to finished foods for flavour(e.g.. butter on bread, salad dressing)

what is waxes composed of?

Long fatty acid and alcohol hydrocarbon chains

is cholesterol an essential nutrient?

NO!

how length of fatty acid is related to melting point?

Shorter carbon chains - more liquid at room temp (lower MP)

what cause rancidity?

TG/fatty acids breakdown into smaller units Accelerated by light, heat and oxygen --> oil used for cooking

what is intersterification

The rearrangement of the fatty acid portion in a triglyceride on the glycerol backbone

how winterization and fractionation are similar to each other ?

The separation of oils into two or more fractions based on melting point

what is the function of waxes, where can we find it?

Waxy coatings are found on leaves and fruit of many plants --> protection fruit and vegetable are artificially waxed to prevent spoilage, water loss and increase shelf-life

how winterization differ to fractionation ?

Winterization: • Oils are cooled and kept at low temperatures for some time, liquid and solids are separated by filtration Fractionation: • Same principle as winterization however it is a more sophisticated process of cooling and separating fractions with much greater control

how long should you keep your refined/monosaturated fat?

about 1 year

what are some origin of lipid?

animals, seeds, nuts, some fruits

how long should you keep your unrefined/polysaturated fat?

around 6 month

what are some good fat for frying ?

beef tallow, palm oil, ghee(high smoke point) - peanut, canola, sunflower, safflower, cottonseed. (350-450 F),

what is the main advantage of intersterification?

can modify the physical properties of a fat without production of trans-fatty acids

what are some food sources of linolenic acid

canola oil, chia seed, flaxseed product, leafy green, ω-3 egg

what are oil that are high in oleic acid?

canola oil, safflower oil, olive oil

how to extract oil?

chemical methods mechanical methods

how cis, trans configuration affect melting point?

cis : more liquid at room temperature, lower MP

what's so special with coconut composition ?

contain mostly medium-chain fatty acids which are metabolized differently by our body

what are oil that are high in linoleic acid?

cottonseed oil, corn oil, soy bean oil

apple sauce work best in

cut calories and fat. replace half butter with apple sauce. use to replace oil in cake, cupcakes and cookies recipes

where we can find naturally occurred trans fatty acid?

dairy product, beef, lamb

where we can find phospholipid in food?

egg yolks, liver, soybeans, wheat germ, peanuts, mustard

what is phospholipid's role (e.g. lecithin) in cooking?

emulsifying agent

glycerol and fatty acid are attached by ___________ linkage to form TG though _________________

ester dehydration synthesis

how oxidative rancidity happen?

exposure of fatty acid to oxygen Three steps: 1. Initiation: free radical is formed --> slow, triggered by light, heat, salt, food particles in frying oil, certain metals (Fe, Cu, Ni) 2. Propagation:oxygen combines with the free radical & peroxide free radical is formed --> domino effect until all double bonds have been used 3. Termination: no more hydrogens at double bonds to react with oxygen

what are some food sources of DHA and EPA?

fatty fish

what is an exception of oil from animal source that is liquid at room temperature?

fish

what areoil that are high in linolenic acid?

flaxseed oil

prune puree

good with chocolate and cinnamon. replace all butter with prune to give low-kcal and low-fat treat

does refined oil tend to have a higher or lower smoke point?

higher

what are two type of rancidity?

hydrolytic and oxidative

what are lard, tallow and suet

lard: pig fat tallow: rendered suet suet: cow, sheep fat

what increase oil's susceptibility to oxidative rancidity?

level of unsaturation (more unsaturated, more susceptible)

beans

mashed or pureed, can replace fat in brownies to give judge like structure. low Kcal, low-fat

banana

mashed, help to reduce fat in muffins and cookies

are ω-6 eicosanoids and ω-3 eicosanoids fatty acid?

no

is consumption of sterol bad?

no, sterol also include phytosterol which can lower cholesterol level in adult

what are some food sources of linoleic acid?

nuts, seeds, vegetable oils, meat

phospholipids have similar in structure to triglycerides --> one FA is replaced by a compound containing ___________ and a _____________________

phosphate nitrogenous base

how do you store butter and margarine?

refrigerator

how do you store unrefined, polyunsaturated oil?

refrigerator, dark glass bottle, airtight

avocado

replace half butter with avocado for a softer and chewier cookies

canola oil

replace half cup melted butter with 1/2 cup canola oil for snack with less saturated fat, ch and na

greek yogurt

replace half cup of butter with 1/4 cup of full fat plain greek yogurt to reduce kcal and saturated fat

how do you store lard, softening, most oil?

room temp, away from light, tightly covered; will keep longer in the refrigerator (esp. olive oil)

tofu

silken tofu replace crea,. low fat and vegan alternative

why coconut is very easy to melt at room temperature?

since coconut oil contain fatty acid that have very short chain length

why flax seed and hemp seed is very hard to be pressed?

since they contain high proportion of omega 3, so very sensitive to heat

how to overcome oxidative stress in food?

use antioxidant

what are some example of antioxidant ?

vitamin E, vitamin C, lecithin, beta-carotene, flavonoid, sulfite, BHA, BHT

what are ways to modify fat?

§ Hydrogenation § Interesterification § Winterization § Fractionation

what are advantages of using solvent to extract oil (chemical)?

• Advantages: highest yield, therefore highest profit, more affordable (most bottled oils and those sold in food products) • Disadvantages: loss of nutrients due to heating of oil (to remove solvent), up to 25ppm of solvent often remains in final product, lower quality oil

what are methods of mechanical extraction?

• Cold-Pressed : highest quality oil, small yields, more expensive, maintains integrity of oil and other compounds within it • Expeller-Pressed: very high pressures, therefore more heat generated

what unrefined oil contain?

• pigments (ex: chlorophyll) • odors and flavors • waxes • Can also contain heavy metals and pesticide residues